1. Field of the Invention
This invention relates to a magnetic bubble memory, and more particularly to a magnetic bubble memory device capable of continuous read-out of information from minor loops in such memory.
2. Description of the Prior Art
Regarding the organizations of magnetic bubble memory devices, a large number of organizations have heretofore been proposed. Among them, what is called the "major-minor loops" organization has been usually employed. Further, there has recently been proposed an organization in which the conventional typical "major-minor loops" organization is modified in order to enhance the read-out cycle time. A typical example of the organization is shown in FIG. 1. Referring to the figure, magnetic bubbles generated by a magnetic bubble generator 1 are propagated on a write-in major line 2 in accordance with a rotating magnetic field. When the magnetic bubbles on the write-in major line 2 have reached the respective positions of write-in gates 4.sub.1 -4.sub.n corresponding to a large number of minor loops 3.sub.1 -3.sub.n, transfer pulses from a transfer pulse source 5 are caused to flow through a conductor 6. Thus, the write-in gates 4.sub.1 -4.sub.n are simultaneously enabled, and the magnetic bubbles on the write-in major line 2 are transferred into the minor loops 3.sub.1 -3.sub.n in information word unit. Thereafter, the magnetic bubbles in the minor loops 3.sub.1 -3.sub.n are circulated therein in accordance with the rotating magnetic field.
Subsequently, the magnetic bubbles circulating within the respective minor loops 3.sub.1 -3.sub.n as lie in positions corresponding to read-out gates 9.sub.1 -9.sub.n of the minor loops 3.sub.1 -3.sub.n are replicated in such a way that replicate pulses from a replicate/transfer pulse source 7 are caused to flow through a conductor 8. At the same time, the replicated magnetic bubbles are transferred onto a read-out major line 10 in the information word unit. Thereafter, the magnetic bubbles are propagated on the read-out major line 10 in accordance with the rotating magnetic field and arrive at an expansion detector 12 having a detecting line 11. Each of the magnetic bubbles is expanded in the lateral direction while propagating in the expansion detector 12, and when it passes through the detecting line 11, the existence thereof is detected as an electric signal.
In a case where most of the information (represented in the forms of the existence and non-existence of the magnetic bubbles) stored in the minor loops 3.sub.1 -3.sub.n are to be read out in the shortest period of time in the magnetic bubble memory organization described above (this case being termed the "continuous read-out"), the continuous read-out has heretofore been carried out in accordance with operational time charts illustrated in FIGS. 2A and 2B. A pulse line shown in FIG. 2A consists of the replicate pulses R.sub.1n at the continuous read-out operation, and they are caused to flow through the conductor 8 by the replicate/transfer pulse source 7. Since the continuous read-out operation is performed, the intervals between the adjacent pulses are constant. FIG. 2B shows strobing pulses D.sub.1n at the time when the magnetic bubbles replicated and transferred from the minor loops 3.sub.1 -3.sub.n onto the read-out major line 10 by the replicate pulses R.sub.1n are detected by the detecting line 11 of the detector 12. That is, the magnetic bubbles in the minor loops 3.sub.1 -3.sub.n are replicated by the first replicate pulse R.sub.11, and the replicated magnetic bubbles are transferred onto the read-out major line 10 in the information word unit. The magnetic bubbles on the read-out major line 10 propagate thereon in accordance with the rotating magnetic field, and after the lapse of a period of time N.sub.11 from the replicate pulse R.sub.11, they reach the detector 12, in which they are successively detected by passing through the detecting line 11. The strobing pulse at this time is that D.sub.11. The information to be subsequently read out as are stored in the minor loops 3.sub.1 -3.sub.n are similarly read out onto the major line 10 by the next replicate pulse R.sub.12. At this time, the information read out by the replicate pulse R.sub.11 are being detected by the detecting line 11 of the detector 12 as apparent from the strobing pulse D.sub.11 in FIG. 2B. Likewise, when the information read out by the replicate pulse R.sub.12 are being detected by the detecting line 11, the next replicate pulse R.sub.13 is generated.
When the replicate pulses R.sub.1n and the strobing pulses D.sub.1n lie in such operational timing relationship, noises ascribable to the replicate pulses R.sub.1n exert influence on the detector 12. This has led to the disadvantage that the noise are superposed on the detection outputs by the detecting line 11, to hinder the normal operation of the detector 12. There may be considered operational timings as shown in FIGS. 2C and 2D wherein, in order to avoid the influence of replicate pulses R.sub.2n at the detection, after all the information read out with the replicate pulse R.sub.21 have passed through the detecting line 11, the next replicate pulse R.sub.22 is generated. With such operational timings, however, a period of time required for reading out necessary information becomes very long, which is not practical.
To the end of solving this problem, operational timings as shown in FIGS. 2E and 2F may be considered. However, a memory organization in which information read out with a replicate pulse R.sub.31 reach the detecting line 11 in a short time N.sub.2 is, in actuality, impossible in view of the construction of the detector 12.